We revisit the process of inverse neutrinoless double beta decay ($e^{-}{e}^{-}\to W^{-}{W}^{-}$) at future linear colliders. The cases of Majorana neutrino and Higgs triplet exchange are considered. We also discuss the processes $e^{-}{\mu }^{-}\to W^{-}{W}^{-}$ and ${\mu }^{-}{\mu }^{-}\to W^{-}{W}^{-}$, which are motivated by the possibility of muon colliders. For heavy neutrino exchange, we show that masses up to ${10}^6$ $({10}^5)\mathrm{GeV}$ could be probed for $ee$ and $e\mu$ machines, respectively. The stringent limits for mixing of heavy neutrinos with muons render ${\mu }^{-}{\mu }^{-}\to W^{-}{W}^{-}$ less promising, even though this process is not constrained by limits from neutrinoless double beta decay. If Higgs triplets are responsible for inverse neutrinoless double beta decay, observable signals are only possible if a very narrow resonance is met. We also consider unitarity aspects of the process in case both Higgs triplets and neutrinos are exchanged. An exact seesaw relation connecting low energy data with heavy neutrino and triplet parameters is found.

Motivated by the new higher D-supergravity solutions on intersecting attractors obtained by Ferrara et al. in [Phys. Rev. D 79, 065031 (2009)], we focus in this paper on 8D maximal supergravity with moduli space $\frac{SL(3,R)}{SO(3)}\times \frac{SL(2,R)}{SO(2)}$ and study explicitly the attractor mechanism for various configurations of extremal black $p$- branes (antibranes) with the typical near horizon geometries ${\mathrm{AdS}}_{p+2}\times S^m\times T^{6-p-m}$ and $p=0$, 1, 2, 3, 4; $2\le m\le 6$. Interpretations in terms of wrapped M2 and M5 branes of the 11D M-theory on 3-torus are also given.

Loop quantum cosmology provides an efficient framework to study the evolution of the Universe beyond the classical Big Bang paradigm. Because of holonomy corrections, the singularity is replaced by a “bounce.” The dynamics of the background is investigated into the details, as a function of the parameters of the model. In particular, the conditions required for inflation to occur are carefully considered and are shown to be generically met. The propagation of gravitational waves is then investigated in this framework. By both numerical and analytical approaches, the primordial tensor power spectrum is computed for a wide range of parameters. Several interesting features could be observationally probed.

We present a simple two-field model of inflation and show how to embed it in string theory as a straightforward generalization of axion monodromy models. Phenomenologically, the predictions are equivalent to those of chaotic inflation, and, in particular, include observably large tensor modes. The whole high-scale large-field inflationary dynamics takes place within a region of field space that is parametrically sub-Planckian in diameter, hence improving our ability to control quantum corrections and achieve slow-roll inflation.

By observing mergers of compact objects, future gravity wave experiments would measure the luminosity distance to a large number of sources to a high precision but not their redshifts. Given the directional sensitivity of an experiment, a fraction of such sources (gold plated) can be identified optically as single objects in the direction of the source. We show that if an approximate distance-redshift relation is known then it is possible to statistically resolve those sources that have multiple galaxies in the beam. We study the feasibility of using gold plated sources to iteratively resolve the unresolved sources, obtain the self-calibrated best possible distance-redshift relation and provide an analytical expression for the accuracy achievable. We derive the lower limit on the total number of sources that is needed to achieve this accuracy through self-calibration. We show that this limit depends exponentially on the beam width and give estimates for various experimental parameters representative of future gravitational wave experiments DECIGO and BBO.

We develop a theoretical framework for describing the hierarchical structure of the phase space of cold dark matter haloes, due to gravitationally bound substructures. Because it includes the full hierarchy of the cold dark matter initial conditions and is hence complementary to the halo model, the stable clustering hypothesis is applied for the first time here to the small-scale phase-space structure. As an application, we show that the particle dark matter annihilation signal could be up to 2 orders of magnitude larger than that of the smooth halo within the Galactic virial radius. The local boost is inversely proportional to the smooth halo density, and thus is $\mathcal{O}(1)$ within the solar radius, which could translate into interesting signatures for dark matter direct detection experiments: The temporal correlation of dark matter detection can change by a factor of 2 in the span of 10 years, while there will be significant correlations in the velocity space of dark matter particles. This can introduce $\mathcal{O}(1)$ uncertainty in the direction of local dark matter wind, which was believed to be a benchmark of directional dark matter searches or the annual modulation signal.

The light-front holographic mapping of classical gravity in anti-de Sitter space, modified by a positive-sign dilaton background, leads to a nonperturbative effective coupling ${\alpha }_s^{\mathrm{AdS}}(Q^2)$. It agrees with hadron physics data extracted from different observables, such as the effective charge defined by the Bjorken sum rule, as well as with the predictions of models with built-in confinement and lattice simulations. It also displays a transition from perturbative to nonperturbative conformal regimes at a momentum scale $\sim 1\mathrm{GeV}$. The resulting $\beta$ function appears to capture the essential characteristics of the full $\beta$ function of QCD, thus giving further support to the application of the gauge/gravity duality to the confining dynamics of strongly coupled QCD. Commensurate scale relations relate observables to each other without scheme or scale ambiguity. In this paper we extrapolate these relations to the nonperturbative domain, thus extending the range of predictions based on ${\alpha }_s^{\mathrm{AdS}}(Q^2)$.

We construct examples of single-sector supersymmetry breaking based on simple deformations of supersymmetric QCD with (weakly) gauged flavor group. These theories are calculable in a weakly coupled Seiberg dual description. In these models, some of the particles in the first two generations of quarks and leptons are composites of the same strong dynamics which leads to dynamical supersymmetry breaking. Such models can explain the hierarchies of Yukawa couplings in the standard model, in a way that predictively correlates with the spectrum of supersymmetry-breaking soft terms.

Based on the stochastic superspace mechanism for softly breaking supersymmetry, we present improved sparticle spectra computations for the minimal model and examine extensions through $R$-parity violation and the type-I seesaw mechanism that incorporate nonzero neutrino masses for more realistic models. Performing the calculations to two-loop accuracy, we observe a global decrease in predicted sparticle masses. However this does not affect the generic features of the minimal model outlined in our earlier work, including the characteristic light stop mass. We find stop decay channels accessible at the LHC which can be used in combination with our predicted range for the stop mixing angle to falsify the minimal model with stochastic supersymmetry. We then introduce neutrino masses and mixings consistent with experiment by including purely trilinear $R$-parity violating superpotential terms, resulting in a viable stochastic superspace model absent a dark matter candidate. An alternative method for generating neutrino masses, namely, the type-I seesaw mechanism, is found only to be viable when the neutrino Yukawa coupling is small relative to the top Yukawa and the cutoff scale is large.

We present the results of computing the order $p^6$ low energy constants in the anomalous part of the chiral Lagrangian for both two and three flavor pseudoscalar mesons. This is a generalization of our previous work on calculating the order $p^6$ coefficients for the normal part of the chiral Lagrangian in terms of the quark self-energy $\Sigma (p^2)$. We show that most of our results are consistent with those we have found in the literature.

Models with large extra dimensions predict the existence of Kaluza-Klein graviton resonances. We compute the next-to-leading-order QCD corrections to graviton plus jet hadro-production, which is an important channel for graviton searches at the Tevatron and the LHC. The QCD corrections are sizable and lead to a significant reduction of the scale dependence. We present numerical results for cross sections and distributions, and discuss the uncertainty from parton distribution functions and the ultraviolet sensitivity of the theoretical prediction.

We study proton-(anti)proton collisions at the LHC or Tevatron in the presence of experimental restrictions on the hadronic final state and for generic parton momentum fractions. At the scale $Q$ of the hard interaction, factorization does not yield standard parton distribution functions (PDFs) for the initial state. The measurement restricting the hadronic final state introduces a new scale ${\mu }_B\ll Q$ and probes the proton prior to the hard collision. This corresponds to evaluating the PDFs at the scale ${\mu }_B$. After the proton is probed, the incoming hard parton is contained in an initial-state jet, and the hard collision occurs between partons inside these jets rather than inside protons. The proper description of such initial-state jets requires “beam functions”. At the scale ${\mu }_B$, the beam function factorizes into a convolution of calculable Wilson coefficients and PDFs. Below ${\mu }_B$, the initial-state evolution is described by the usual PDF evolution which changes $x$, while above ${\mu }_B$ it is governed by a different renormalization group evolution that sums double logarithms of ${\mu }_B/Q$ and leaves $x$ fixed. As an example, we prove a factorization theorem for “isolated Drell-Yan”, $pp\to X{\ell }^{+}{\ell }^{-}$ where $X$ is restricted to have no central jets. We comment on the extension to cases where the hadronic final state contains a certain number of isolated central jets.

Heavy charged lepton productions via gluon fusion at the LHC are revisited. Full loop calculations are adopted with an updated parton distribution function and electroweak data. Including contribution from new generation quarks in the loop, pair production of the sequential heavy lepton via gluon fusion at the LHC dominates over that via the Drell-Yan mechanism in some heavy lepton mass range. Exotic lepton single production of vectorlike lepton extended models is also calculated. In the later case, the gluon fusion mechanism via the Higgs exchange is emphasized. Our numerical results for both pair and single production of heavy leptons are smaller than previous studies especially for a large heavy lepton mass as a result of full loop calculation and due to the mixing angles.

It was recently realized that three-flavor effects could peculiarly modify the development of spectral splits induced by collective oscillations, for supernova neutrinos emitted during the cooling phase of a protoneutron star. We systematically explore this case, explaining how the impact of these three-flavor effects depends on the ordering of the neutrino masses. In inverted mass hierarchy, the solar mass splitting gives rise to instabilities in regions of the (anti)neutrino energy spectra that were otherwise stable under the leading two-flavor evolution governed by the atmospheric mass splitting and by the 1–3 mixing angle. As a consequence, the high-energy spectral splits found in the electron (anti)neutrino spectra disappear, and are transferred to other flavors. Imperfect adiabaticity leads to smearing of spectral swap features. In normal mass hierarchy, the three-flavor and the two-flavor instabilities act in the same region of the neutrino energy spectrum, leading to only minor departures from the two-flavor treatment.

We derive a factorization theorem for the Higgs boson transverse momentum ($p_T$) and rapidity ($Y$) distributions at hadron colliders, using the soft-collinear effective theory (SCET), for $m_h\gg p_T\gg {\Lambda }_{\mathrm{QCD}}$, where $m_h$ denotes the Higgs mass. In addition to the factorization of the various scales involved, the perturbative physics at the $p_T$ scale is further factorized into two collinear impact-parameter beam functions (IBFs) and an inverse soft function (ISF). These newly defined functions are of a universal nature for the study of differential distributions at hadron colliders. The additional factorization of the $p_T$-scale physics simplifies the implementation of higher order radiative corrections in ${\alpha }_s(p_T)$. We derive formulas for factorization in both momentum and impact parameter space and discuss the relationship between them. Large logarithms of the relevant scales in the problem are summed using the renormalization group equations of the effective theories. Power corrections to the factorization theorem in $p_T/m_h$ and ${\Lambda }_{\mathrm{QCD}}/p_T$ can be systematically derived. We perform multiple consistency checks on our factorization theorem including a comparison with known fixed-order QCD results. We compare the SCET factorization theorem with the Collins-Soper-Sterman approach to low-$p_T$ resummation.

A high-statistics sample of charged-current muon neutrino scattering events collected with the MiniBooNE experiment is analyzed to extract the first measurement of the double differential cross section ($\frac{d^2\sigma }{d{T}_{\mu }d\cos {\theta }_{\mu }}$) for charged-current quasielastic (CCQE) scattering on carbon. This result features minimal model dependence and provides the most complete information on this process to date. With the assumption of CCQE scattering, the absolute cross section as a function of neutrino energy ($\sigma [E_{\nu }]$) and the single differential cross section ($\frac{d\sigma }{d{Q}^2}$) are extracted to facilitate comparison with previous measurements. These quantities may be used to characterize an effective axial-vector form factor of the nucleon and to improve the modeling of low-energy neutrino interactions on nuclear targets. The results are relevant for experiments searching for neutrino oscillations.

We search for the flavor-changing neutral current decays $D^0\to {\mu }^{+}{\mu }^{-}$ and $D^0\to e^{+}{e}^{-}$, and for the lepton-flavor violating decays $D^0\to e^{\pm }{\mu }^{\mp }$ using $660{\mathrm{fb}}^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We find no evidence for any of these decays. We obtain significantly improved upper limits on the branching fractions: $\mathcal{B}(D^0\to {\mu }^{+}{\mu }^{-})<1.4\times {10}^{-7}$, $\mathcal{B}(D^0\to e^{+}{e}^{-})<7.9\times {10}^{-8}$, and $\mathcal{B}(D^0\to e^{+}{\mu }^{-})+\mathcal{B}(D^0\to {\mu }^{+}{e}^{-})<2.6\times {10}^{-7}$ at 90% confidence level.

We consider a four-dimensional theory in the $z=3$ Lifshitz context, with an exponential (Liouville) potential. We determine the exact renormalized potential of the theory and derive the nonperturbative relation between the renormalized and bare couplings. In addition, we show that Lorentz symmetry is naturally generated by quantum fluctuations in the infrared regime, and conclude that the model can be relevant to high energy physics.

Ultrarelativistic collisions of black holes are ideal gedanken experiments to study the nonlinearities of general relativity. In this paper we use semianalytical tools to better understand the nature of these collisions and the emitted gravitational radiation. We explain many features of the energy spectra extracted from numerical relativity simulations using two complementary semianalytical calculations. In the first calculation we estimate the radiation by a “zero-frequency limit” analysis of the collision of two point particles with finite impact parameter. In the second calculation we replace one of the black holes by a point particle plunging with arbitrary energy and impact parameter into a Schwarzschild black hole, and we explore the multipolar structure of the radiation paying particular attention to the near-critical regime. We also use a geodesic analogy to provide qualitative estimates of the dependence of the scattering threshold on the black hole spin and on the dimensionality of the spacetime.

In this paper we present the results of $N$-body simulations with a scalar field coupled differently to cold dark matter (CDM) and baryons. The scalar field potential and coupling function are chosen such that the scalar field acquires a heavy mass in regions with high CDM density and thus behaves like a chameleon. We focus on how the existence of the scalar field affects the formation of nonlinear large-scale structures, and how the different couplings of the scalar field to baryons and CDM particles lead to different distributions and evolutions for these two matter species, both on large scales and inside virialized halos. As expected, the baryon-CDM segregation increases in regions where the fifth force is strong, and little segregation in dense regions. We also introduce an approximation method to identify the virialized halos in coupled scalar field models which takes into account the scalar field coupling and which is easy to implement numerically. It is found that the chameleon nature of the scalar field makes the internal density profiles of halos dependent on the environment in a very nontrivial way.